Immunology Flashcards
What are the differences between the innate and adaptive immune systems?
Innate is quick to respond Adaptive is more specific Innate is present at birth Adaptive has good memory Innate detects alterations in haemostasis Adaptive is humoral and cell mediated
What innate immunological cells are there?
Blood -monocyte -basophil -eosinophil -neutrophil -natural killer cell Tissue -dendritic cells -macrophages -mast cell
How do macrophages, dendritic and mast cells affect invading cells?
They release cytokines to attract other cells and dilates the arteries to get more blood flow, and get adhesions to stick things
Can phagocytose cells
What are the functions of the innate system?
Phagocytosis
Antigen presentation to communicate between the adaptive system
Natural killer cell releases perforin and granzyme
Inflammation
Opsonisation
What is MHC1 and 2?
MHC1- all nucleated cells have it (and platelets which don’t have nucleus), recognised by CD8
MHC2- antigen presenting cells have it, recognised by CD4
Major Histocompatibility Complex
What are the cells of the adaptive immune system?
T cells (helper, regulatory and cytotoxic) B cells (can differentiate into plasma cells)
What are cytokines and what do they do?
Large and heterogeneous soluble proteins
Communication system – act locally or at a distance
Regulate and co-ordinate the cells of innate and adaptive immunity ie regulate immune responses
Produced during normal haematopoiesis
Produced in response to microbes, tissue damage or other antigens
Produced by many cell types – esp macrophages and T helper cells
How do CD8 cells kill other cells?
The cytokines produced by the CTL do not cause killing of the cell directly, they will e.g. induce the actions of phagocytic clearance.
CD8 cells kill via perforin and granzyme or FasL pathway
How do Natural killer cells kill other cells?
If MHC presentation is normal then NK cells will leave alone, but if too low (cancer) or not wrong then NK will induce apoptosis
Same killing mechanism as CD8
When in life does each antibody start being produced?
IgM produced as fetus, IgG not til birth, IgA not until 1-2 months after birth
Breast milk contains IgA
What is the activity of the complement immune system>
Chemotaxis of phagocytes to sites of inflammation
Opsonisation
Lysis of micro-organisms
Maintain solubility of Ag / Ab complexes
What lineage is the natural killer cell from?
Lymphoid (but involved in innate immune system)
What is involved in the process of negative and positive selection in T lymphocytes?
Positive selection involves selecting T lymphocytes with T cell receptors capable of interacting appropriately with host MHC molecules. If the double positive thymocytes are able to interact with the MHC, they survive. If they are unable to interact with the MHC, they are destroyed by apoptosis. Negative selection involves identifying thymocytes that interact too strongly with self antigens within the thymus. Thymocytes that react too strongly, are destroyed by apoptosis
How are T regulatory cells formed and what do they do?
During selection of T cells in the thymus, some T cells that recognise self-antigens are not deleted and differentiate into regulatory T cells that are specific for that antigen. They are responsible for suppressing the activation, proliferation and cytokine production of CD4 and CD8. They control the response to self-antigens, and in this way monitor the process of self-tolerance. They secrete IL-10 and Transforming growth factor-beta (TGF-b), which are anti-inflammatory and help to suppress the immune response.
What cells produce antibodies?
Plasma cells
Which antibody is a pentomer?
IgM
What are the functions of antibodies?
They can bind to antigens directly to form immune complexes, which can be cleared through filtration of the blood in organs like the liver and spleen.
Antibodies also act as opsonins for phagocytosis. Antibodies are capable of activating the complement cascade via the Classical pathway.
Antibodies can bind to target cells and initiate a non-phagocytic cell-mediated destruction of these cells. This is called Antibody-dependent cellular cytotoxicity (ADCC)
What antibody provides a primary and secondary response with the secondary response being larger?
IgG
What is the immunological memory?
After the primary infection by a pathogen, a small pool of long-lived memory B and T cells specific to the pathogen’s antigen remain quiescent within the body. Memory cells can lie dormant for many years but are poised to respond rapidly if reinfection occurs.
Name two pattern recognition receptors
Toll-like receptors (TLRs)
C-type lectin receptors (CLRs)
What cells can phagocytose other cells?
Macrophage Dendritic cell Monocyte Mast cell Neutrophil
What are three pathways that can activate the complement cascade?
Classical pathway (antibodies and antigens)
Lectin pathway
Alternative pathway
What pathogen does each immune cell target?
Neutrophils – bacterial & fungal infection
Monocytes – fungal infection
Eosinophils – parasitic infections
T lymphocytes – fungal & viral infection, PJP
B lymphocytes – bacterial infection
What is G-CSF used for?
G-CSF is used to reduce neutropenia
What drugs should be used to treat a neutropenic sepsis?
Broad spectrum I.V. antibiotics
- Tazocin and Gentamicin
If a gram positive organism is identified add vancomycin or teicoplanin
If no response at 72 hours add I.V. antifungal treatment e.g. Caspofungin
What are the two types of immunodeficiency?
Primary, or congenital, immunodeficiencies
Secondary, or acquired, immunodeficiencies
What are patients more susceptible to if they are immunodeficient?
The major consequence of immunodeficiency is increased susceptibility to infection.
Patients with immunodeficiencies are also susceptible to certain types of cancer.
Certain immunodeficiencies are associated with an increased incidence of autoimmunity
What immune defect is present if there is repeated infection with an encapsulated bacteria?
defective antibody production.
